GD32W51x User Manual
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PA15 : JTDI
PA14 : JTCK/SWCLK
PA13 : JTMS/SWDIO
PB4 : NJTRST
PB3 : JTDO
By default, 5-pin standard JTAG debug mode is chosen after reset. Users can also use JTAG
function without NJTRST pin, then the PB4 can be used to other GPIO functions. (NJTRST
tied to 1 by hardware). If switch to SW debug mode, the PA15/PB4/PB3 are released to other
GPIO functions. If JTAG and SW not used, all 5-pin can be released to other GPIO functions.
Please refer to
13.2.3.
JTAG daisy chained structure
The Cortex-M33 JTAG TAP is connected to a Boundary-Scan (BSD) JTAG TAP. The BSD
JTAG IR is 5-bit width, while the Cortex-M33 JTAG IR is 4-bit width. So when JTAG in IR shift
step, it first shift 5-bit BYPASS instruction (5’b 11111) for BSD JTAG, and then shift normal 4-
bit instruction for Cortext-M33 JTAG. Because of the data shift under BSD JTAG BYPASS
mode, adding 1 extra bit to the data chain is needed.
The BSD JTAG IDCODE is 0x790007A3.
13.2.4.
Debug reset
The JTAG-DP and SW-DP register are in the power on reset domain. The System reset
initializes the majority of the Cortex-M33, excluding NVIC and debug logic, (FPB, DWT, and
ITM). The NJTRST reset can reset JTAG TAP controller only. So, it can perform debug feature
under system reset. Such as, halt-after-reset, which is the debugger sets halt under system
reset, and the core halts immediately after the system reset is released.
13.2.5.
JEDEC-106 ID code
The Cortex-M33 integrates JEDEC-106 ID code, which is located in ROM table and mapped
on the address of 0xE00FF000_0xE00FFFFF.
13.3.
Debug hold function description
13.3.1.
Debug support for power saving mode
When STB_HOLD bit in DBG control register 0 (DBG_CTL0) is set and entering the standby
mode, the clock of AHB bus and system clock are provided by CK_IRC16M, and the debugger
can debug in standby mode. When exit the standby mode, a system reset generated.
When DSLP_HOLD bit in DBG control register 0 (DBG_CTL0) is set and entering the Deep-
sleep mode, the clock of AHB bus and system clock are provided by CK_IRC16M, and the
debugger can debug in Deep-sleep mode.
Содержание GD32W515 Series
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